[Dmitry Grinberg] has to walk all the way across his bedroom to switch the lamp on and off. The drudgery of this finally became too much, so he built a remote control and added dimming for good measure. Above you can see the circuitry for the remote and the receiver, as well as the finished remote housed in what he calls a ‘Chinese Altoids tin’.

After the break you’ll find [Dmitry's] demo video. The remote control is quite responsive, and the dimming has great resolution. That’s thanks to a power N-channel MOSFET which switches the AC with the help of a full wave rectifier. The PIC 12F617 that controls the MOSFET is powered separately, and [Dmitry] mentions that you must use a transformer and not a switch-mode power supply to avoid a fire. We’d like to know more about this, so leave a comment if you are able to explain further.

The remote and receiver communicate via Infrared. The protocol is operating with 38 kHz signals using an easily sourced receiver tuned to that frequency. [Dmitry] shares all the details about the encoding scheme that he uses. Recreating this communications pairing is a great way to test your understanding of this technique. But if you need a refresher, here’s a tutorial to push you in the right direction. Read the rest of this entry »

You might want to store information from a multimeter to be graphed over time. This comes with pretty much all of the high-end professional models. But if you buy a super cheap meter you can bet this isn’t an option. [Jazzzzzz] has found a way to pull the data from a $4 meter via RS232. It’s not impossible, but we definitely think he’s doing it the hard way. That’s because he’s not just tapping into a dormant feature. He’s actually adding a microcontroller to sample the data and push it via the RS232 protocol.

On the bright side, this is easier than building a multimeter from scratch. The sampling circuits are still being used, with a PIC 16F688 intercepting the signals as they enter the stock microcontroller. The signal he was after comes into the chip on just one pin, but to get the readings right on the PIC he had to use an OpAmp. That’s only part of the puzzle as he also needed a way to tell what the selector switch was set at. In the end, adding a potentiometer and reading its value let him calculate the position.

[Thanks Karl]

[Gary] had an RF triggered light switch kicking around, and wanted to find a way to control his lights using a home theater remote. The switch, which he bought from RadioShack years ago, came with a simple remote that uses two buttons to toggle the lights on and off. While you might think that switching from RF to IR control would be a step backwards, [Gary] really just wanted to consolidate remotes more than anything else.

He designed a circuit board specifically for interacting with the remote half of his RF controller. It sports a PIC16F628A micro controller, which is tasked with processing IR commands from his home theater remote and triggering the lights when requested.

The code he developed for the project is relatively simple, but very useful all the same. When his board is powered on, it stores the first IR code it receives, then retains it as long as it stays powered on. This lets [Gary] use any button on his remote to turn the lights on and off, without any IR codes permanently defined in software.

As you can see in the video below, the modified switch works just as intended, saving [Gary] from having to walk all the way to the light switch when it’s time to fire up a movie.

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Sometimes you just don’t have space for a baby grand. [Abdullah] got around this problem and built a virtual wireless MIDI piano. Unlike it’s inspiration, it’s not bad but we still love it.

[Abdullah] got his hands on some flex sensors and attached them to a glove. These resistive sensors are put through a voltage divider and sent to a microcontroller (a PIC16F778, we believe) and corresponding MIDI notes are chosen. These MIDI notes are sent to a computer and played over a speaker.

Right now, only a single arpeggio is coded into the microcontroller. Depending on which finger is bent shifts this arpeggio up and down the keyboard. That being said, the firmware can be easily modified to recognize standard piano fingering so chords can be played. The only issue is moving the hand up and down the keyboard.

[Abdullah] is planning on making his glove completely wireless with a microcontroller and battery sewn into the glove. Here’s to hoping he’ll keep us posted.

Check out [Abdullah]‘s demo after the break.

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[Blaise Jarrett] has been grinding away to get the WebSocket protocol to play nicely with PIC microcontrollers. Here he’s using the PIC 18F4620 along with a Roving Networks RN-XV WiFi module to get the device on the network. He had started with a smaller processor but ran into some RAM restrictions so keep that in mind when choosing your hardware.

This project was spawned after seeing the mBed feature a few days back which combined that board along with a WebSocket library and HTML5 to pull off some pretty amazing stuff. [Blaise] doesn’t have quite as much polish on the web client yet, but he has recreated the data transfer method and improved on that project by moving to the newer version 13 of WebSockets. The protocol is kind of a moving target as it is still in the process of standardization.

The backend is a server called AutoBahn which is written in python. It comes along with client-side web server examples which gave him a chance to get up and running quickly. From there he got down to work with the WebSocket communications. They’re a set of strings that look very much like HTML headers. He outlines each command and some of the hangups one might run into with implementation. After reading what it takes to get this going it seems less complicated than we thought, but it’s obvious why you’ll need a healthy chunk of RAM to pull it off.

[Chris] just posted his latest tutorial which shows you how to read position data from a resistive touchscreen. These devices are fairly simple, and since they’re used in a lot of consumer electronics you can pick one up for a few bucks. This looks like it is overstock for an old Palm device.

The interface is simple, there’s just four conductors on the tab at the top of the overlay. But connecting to these is a bit of an issue since you can’t really solder directly to them. [Chris] ended up using scotch-tape to hold wires in place, with a paperclip to keep them presses against the conductors. Those conductors are used in pairs, with a positive and negative lead for the X and Y axis. To take a measurement you use I/O pins to connect voltage and ground, then read the voltage that makes it to the gound side using an ADC. This works because the point that’s being pressed on the screen acts as a variable resistor for the circuit. Data for the two axes must be read in separate operations so that the positive voltages don’t interfere with each other.

The nice thing is that once you’ve got it working with a small screen it is easily scaled up. In fact, the 23″ touchscreen used on this Android hack is just another 4-wire resistive device.

You can see a video demonstration of [Chris'] test rig embedded after the break.

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[Marcus Gritsch] wanted to do his retro gaming using retro hardware… or at least using some retro hardware. Although he was playing his Commodore 64 games in an emulator, he figured that using an original controller would boost the nostalgia quite a bit. This is a vintage Competition Pro joystick that has buttons and a joystick of a similar quality to arcade hardware and a DE-9 connector. He managed to connect new to old by building his own USB to C64 joystick adapter.

His project started out by breadboarding a circuit based on a PIC 24FJ64GB002 microcontroller. This does all of the work, having native USB support, and no problem reading and translating the signals from the old hardware which are simply conductors for each internal switch that pull to ground when actuated. Once working, he soldered everything to some protoboard; a connector at each end, the chip itself, a voltage regulator, and some passive components. It’s a, robust build that should give him years of emulated fun.

[Rajendra] found an easy way to make a USB temperature logger. He already had a USB to UART adapter that takes care of the heavy lifting. On one end it’s got the USB plug, on the other a set of pins provide a ground connection, 3.3V and 5V feed, as well as RX/TX lines.

To get the hardware up and running all he needed was something to read a temperature sensor and push that data over the serial connection. An 8-pin microcontroller in the form of a PIC 12F1822 does the trick. It runs off of the 5V pin on the USB-UART, and uses the ADC to get temperature data from an MCP9701A sensor.

The sample rate is hard-coded into to the PIC’s firmware, but adding a button, or coding some serial monitoring could easily make that configurable. [Rajendra] used Processing to write an app which displays the incoming temperature info and uses the computer to time-stamp and log the inputs. We could see this as a quick solution to tracking wort temperature during fermentation to make sure your beer comes out just right.